A solenoid is a device that converts electrical energy into mechanical work. Solenoids are constructed of a free moving steel plunger that sits within one or more wound coils of copper wire. When electric current is introduced, a magnetic field forms that draws the plunger in. The exposed end of the plunger can be attached to equipment and when the solenoid is activated, the plunger moves to open, turn on, or turn off that equipment. Solenoids are used for operating engine run/stop levers, throttles, chokes, valves and clutches and to protect expensive diesel engines from overspeed conditions, low lube pressure, and high temperature. Dual coil solenoids use two separate coil windings to allow the solenoid to be held energized for long periods of time without overheating. The first wound coil (pull coil) operates at a high current level to provide maximum pull or push. The second wound coil (hold coil) holds the plunger in place after it has completed its stroke.
Some solenoids include a mechanical switch having mechanical contacts that open when energized to disconnect from the pull coil after the plunger has been retracted. The mechanical contacts may include bushings that have a tendency to burn out. Electronically pulse width modulated driven solenoids eliminate the need for the mechanical switch and its associated problems and eliminate the need for the second hold coil. Instead, the electronically driven solenoids include solenoid driver circuitry that typically has a 4.5 Volt to 5.0 Volt minimum operating voltage requirement. Low cost voltage regulators that provide the battery voltage to the integrated circuit typically have a 0.7 Volt to 1.0 Volt voltage drop. Accordingly, if a battery voltage is run down under 5.2 Volts to 6.0 Volts, the solenoid driver circuitry may stop functioning and the solenoid may shut down. Preventing solenoid shut down by using larger battery voltages or voltage regulators having lower voltages drops to achieve solenoid driver circuitry minimum operating voltage requirements may be expensive and can take up valuable space, precluding these options from being commercially viable.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present disclosure as set forth in the remainder of the present application with reference to the drawings.